Simulation of ab initio results for palladium and rhodium clusters by tight-binding calculations

Abstract

The study of metal clusters is nowadays a very active field of research using both experimental and theoretical techniques. Regular trends as well as unexpected behaviors have been observed regarding size-dependent properties such as ionization potentials and atomization energies. Palladium and rhodium clusters of small size have been extensively studied at various semiempirical and ab initio levels of the theory, but the achievement and the interpretation of these calculations are generally difficult to be performed because of the incomplete shell structure of transition metal clusters. So we have tried to mimic the most important conclusions of the ab initio results available for Pd and Rh clusters by means of tight-binding calculations, in the original Wolfsberg–Helmholz form, with appropriate parametrized repulsion terms. The occupation numbers of the one-electron energy levels have been determined by taking into account some predictions of the graph theory. This enables us to study the variation of the atomization energies per atom for these clusters and to derive a bond-energy systematics for Pd–Pd, Rh–Rh, and Pd–Rh linked atoms. Magic clusters with 13 atoms are considered. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 26–33, 2001